1. Field of the Invention
The present invention relates to a temperature controlling apparatus that controls the temperature of a temperature-controlling object such as a heat transfer plate by cooling the heat transfer plate using a coolant of a coolant circulating apparatus and heating the heat transfer plate using an electrothermal heater.
2. Description of the Related Art
Conventionally, a temperature controlling apparatus that controls the temperature of a temperature-controlling object such as a heat transfer plate uses a coolant circulating apparatus to circulate a coolant through a cooling path arranged at the temperature-controlling object to cool the temperature-controlling object, and uses an electrothermal heater that is arranged at the temperature-controlling object to heat the temperature-controlling object. For example, the temperature of the temperature-controlling object may be controlled to be within a range of −70° C. to 200° C. FIG. 1 is a circuit diagram showing an exemplary configuration of a temperature controlling apparatus including a coolant circulating apparatus.
In FIG. 1, the temperature of a temperature-controlling object such as a heat transfer plate P′ is controlled. Specifically, the heat transfer plate P′ may be cooled by a coolant 104 (referred to as ‘cooling liquid 104’ hereinafter) of a coolant circulating apparatus that is cooled at a refrigerator 101 and is circulated through a cooling path 108 arranged at the heat transfer plate P′, or the heat transfer plate P′ may be heated by a heat transfer plate heater 109 installed in the heat transfer plate P′. It is noted that the heat transfer plate P′ is normally positioned so that the cooling path 108 may be substantially horizontal.
The refrigerator 101 includes a compressor 102 and a heat exchanger 103. It is noted that a circulating circuit is formed in the refrigerator 101 for circulating a coolant (referred to as ‘refrigerator side coolant’ hereinafter) through the compressor 102→the heat exchanger 103→the compressor 102 in the direction indicated by the arrows shown in FIG. 1. The heat exchanger 103 includes a refrigerator side coolant path 103a where the refrigerator side coolant is circulated and a cooling liquid path 103b where the cooling liquid 104 that cools the heat transfer plate P′ is circulated. It is noted that when the cooling liquid 104 passes through the cooling liquid path 103b, heat may be transferred from the cooling liquid 104 to the refrigerator side coolant that is cooled at the refrigerator 101 so that the cooling liquid 104 may be cooled.
The coolant circulating apparatus that controls the temperature of the heat transfer plate P′ includes a low temperature tank 105 that stores the cooling liquid 104, a circulating pump 106 that circulates the cooling liquid 104, a cooling liquid heater 107 having an electrothermal heater for heating the cooling liquid 104 stored in the low temperature tank 105, the cooling path 108 arranged at the heat transfer plate P′, and the cooling liquid path 103b arranged at the heat exchanger 103. In the coolant circulating apparatus, a circulating circuit is formed by a circulating line L′ that circulates the cooling liquid 104 through the low temperature tank 105→the circulating pump 106→the cooling path 108 of the heat transfer plate P′→the cooling liquid path 103b of the heat exchanger 103→the cooling liquid heater 107→the low temperature tank 105 in the direction indicated by the arrows shown in FIG. 1. The heat transfer plate heater 109 is installed in the heat transfer plate P′, and is controlled based on the temperature detected by a temperature sensor 109a arranged at the heat transfer plate P′ to heat the heat transfer plate P′ to a predetermined temperature.
In the following, operations of the coolant circulating apparatus of FIG. 1 are described. In the case of controlling and adjusting the temperature of the heat transfer plate P′ to a temperature higher than 40° C., operations of the circulating pump 106 are stopped, and the heat transfer plate heater 109 installed in the heat transfer plate P′ is activated. The heat transfer plate heater 109 controls the temperature of the heat transfer plate P′ to be a predetermined temperature based on the temperature detected by the temperature sensor 109a that is arranged at the heat transfer plate P′.
In the case of controlling the temperature of the heat transfer plate P′ to be a temperature that is less than or equal to 40° C., the circulating pump 106 is operated. The circulating pump 106 transfers the cooling liquid 104 accommodated in the low temperature tank 105 to the cooling path 108. In this way, heat is transferred from the heat transfer plate P′ to the cooling liquid 104 transferred to the cooling path 108. Then, the cooling liquid 104 within the cooling path 108 is transferred to the cooling liquid path 103b of the cooling heat exchanger 103 where heat transfer occurs from the cooling liquid 104 to the refrigerator side coolant flowing through the refrigerator side coolant path 103a so that the cooling liquid 104 may be cooled. Then, the cooling liquid 104 is transferred back to the low temperature tank 105 via the cooling liquid heater 107. In this way, the cooling liquid 104 circulates around the circulating line L′ so that the temperature of the cooling liquid 104 within the low temperature tank 105 may be gradually decreased. It is noted that the temperature of the cooling liquid 104 within the low temperature tank 105 is monitored by a temperature sensor 107a arranged at the low temperature tank 105. When the temperature of the cooling liquid 104 within the low temperature tank 105 is cooled to a temperature below the desired temperature (predetermined temperature), the cooling liquid heater 107 is driven based on the detected temperature of the temperature sensor 107a to maintain the temperature of the cooling liquid 104 in the low temperature tank 105 at the predetermined temperature. It is noted that in certain specific examples, temperature control of the cooling liquid 104 in the low temperature tank 105 may be performed using a flow rate adjusting valve as is illustrated in FIG. 1 of Japanese Laid-Open Patent Publication No. 2003-148852 or a heater arranged at a low temperature tank as is illustrated in FIG. 2 of the same document.
The heat transfer plate P′ is cooled by the cooling liquid 104 in the low temperature tank 105 that is maintained at the predetermined temperature and is circulated through the cooling path 108 of the heat transfer plate P′. It is noted that the temperature of the heat transfer plate P′ is monitored by the temperature sensor 109a, and the heat transfer plate heater 109 is controlled based on the temperature detected by the temperature sensor 109a. Accordingly, the temperature of the heat transfer plate P′ may be lowered by the cooling liquid 104 and raised by the heat transfer plate heater 109 to be controlled at the predetermined temperature.
As is mentioned above, Japanese Laid-Open Patent Publication No. 2003-148852 discloses technology related to a temperature controlling apparatus. Japanese Laid-Open Patent Publication No. 2002-124558 and Japanese Laid-Open Patent Publication No. 2002-353297 disclose technology related to a heat transfer plate.
It is noted that in the case of controlling the temperature of the heat transfer plate P′ to become a high temperature above 90° C., for example, the temperature controlling apparatus as is described above stops the operation of the circulating pump 106 and uses the heat transfer plate heater 109 to increase the temperature of the heat transfer plate P′. However, since the cooling liquid 104 remains in the cooling path 108 of the heat transfer plate P′, the heat capacity of the heat transfer plate P′ may be relatively large and a relatively long period of time may be required to increase the temperature of the heat transfer plate P′ using the heat transfer plate heater 108.
Further, in the case of controlling the temperature of the heat transfer plate P′ to become an even higher temperature of over 150° C. such as 200° C., depending on the type of cooling liquid used or the temperature conditions of the cooling liquid, evaporation or oxidation of the cooling liquid may occur, or poisonous gas may be generated due to the fact that the cooling liquid 104 remains within the cooling path 108 of the heat transfer plate P′. Such a problem may occur upon controlling the heat transfer plate P′ to become a high temperature particularly in a case where a coolant that is effective in a low temperature range (e.g. less than or equal to 0° C.) is used.